Changing users on an iPad

My 7YO started using my wife’s old iPad some years ago. At some point we migrated him to a new iPad, but it continued to be logged into her iCloud account.

I now have iCloud family set up, and I established a child account in his name. I set the iPad to use that iCloud account instead of my wife’s account. All the apps stayed in place (which I would prefer), but any attempt to update apps requires both my wife’s iCloud password and a two-factor authentication code from her account–for each app, separately.

I suspect I could work around this by deleting each app (plus its data) and then re-installing it from his login since we have the family set up. But I’m wondering if there’s any simpler way that preserves his app data but allows him to get updates without a lot of extra hassle. Alternatively, if there’s a way I could use her account info one time to set up automatic app updates in the future, that would probably also be straightforward.

Has anyone out there managed the transition of a kid’s device from using a parent’s iCloud account to using the child’s iCloud account, and have any suggestions how to make it as painless as possible?